The present invention relates to a planetary gear mechanism. More particularly, the present invention pertains to a construction for a lubrication of a planetary gear mechanism.
Known planetary gear mechanisms applied to automatic transmissions and center differential gears include a sun gear, a ring gear, a plurality of pinion gears geared between the sun gear and the ring gear, and a carrier for supporting the pinion gears. An external peripheral surface of each pinion gear is formed with a gear engaged with a tooth flank of the sun gear and the ring gear. A pinion pin is rotatably inserted into an internal periphery of each pinion gear via a rolling bearing. By fixing an axial end portion of the pinion pin to the carrier, the pinion gears are supported by the carrier.
The known planetary gear mechanisms of the foregoing construction includes a radial slit provided on the carrier and a bore provided in the pinion pin so that the slit and the bore are in communication each other. With this construction, when the centrifugal force affects, the lubrication oil in the sun gear is introduced into between the pinion pin and the pinion gear and into geared portions between the pinion gear, the sun gear, and the ring gear so that the lubrication of the planetary gear mechanism is performed.
Notwithstanding, with the foregoing known construction, washers provided between the pinion gear and the carrier are rotated about the pinion pin. This may cause the burning and the damage between the washers and the carrier or between the washers and the pinion gears.
A need thus exists for a planetary gear mechanism which securely performs the lubrication performance thereof.
In light of the foregoing, the present invention provides a planetary gear mechanism which includes a sun gear having an introduction passage for introducing a lubrication fluid in an axial direction and a communication passage for communicating the introduction passage and an outside of the sun gear, a ring gear provided coaxial to the sun gear, a plurality of pinion gears geared with the sun gear and the ring gear, a plurality of pinion pins provided in an internal peripheral side of the pinion gears to be coaxial to and rotatable relative to the pinion gears, a carrier having a penetration bore inserted with an axial end of the pinion pin for supporting the pinion pins so that the pinion gears rotate about the sun gear, a washer provided between the pinion gear and the carrier being inserted with the pinion pin, a slit formed on the carrier formed radially inward relative to the penetration bore, the slit being formed facing the washer on an identical plane surface with the communication passage corresponding to a surface perpendicular to the axial direction, a restriction portion formed on the washer for restricting rotational movement of the washer relative to the carrier, and an extension portion formed on the washer and extended in radially inward direction relative to the penetration bore and radially inward relative to a tooth flank of the pinion gear.